Tony,
This format did not lend itself to discussion of the technical reasons for the collapse. In fact the girder walk off, in my opinion even if it did occur... would not lead to the 1000#/ft column from buckling. THAT I believe has not been shown. Sure columns which require and lose lateral bracing could buckle if the unsupported length is long enough slenderness ratio too high... but this has not been shown to be the case as far as I can tell.
As I told Richard before the presentation I think NIST did not come up with a convincing case for how that collapse initiated. But to jump the conclusion that the collapse was CD because the curtain wall which was twisted (rotated counter clockwise) and quite bowed collapsed from the 8th floor to the ground at close to FF is smoking gun evidence of 8 floors of 83 columns being destroyed in "an instant" is just false. That is a very very irresponsible and stupid statement.
And for the millionth time... the collapse was not symmetrical and symmetry would mean nothing if it were. A building will collapse straight down unless pushed over and there was nothing exerting a lateral force on that building. It collapsed because the structure came apart at it's base.
This format did not lend itself to discussion of the technical reasons for the collapse. In fact the girder walk off, in my opinion even if it did occur... would not lead to the 1000#/ft column from buckling. THAT I believe has not been shown. Sure columns which require and lose lateral bracing could buckle if the unsupported length is long enough slenderness ratio too high... but this has not been shown to be the case as far as I can tell.
As I told Richard before the presentation I think NIST did not come up with a convincing case for how that collapse initiated. But to jump the conclusion that the collapse was CD because the curtain wall which was twisted (rotated counter clockwise) and quite bowed collapsed from the 8th floor to the ground at close to FF is smoking gun evidence of 8 floors of 83 columns being destroyed in "an instant" is just false. That is a very very irresponsible and stupid statement.
And for the millionth time... the collapse was not symmetrical and symmetry would mean nothing if it were. A building will collapse straight down unless pushed over and there was nothing exerting a lateral force on that building. It collapsed because the structure came apart at it's base.
Attachments
Last edited:
